Tension apparatus in the endless forming wire of a fourdrinier paper machine



July 4, 1967 w. E. ROJECKI ETAL 3,329,561

TENSION APPARATUS IN THE ENDLESS FORMING WIRE OF A FOURDRINIER PAPER MACHINE Flled Sept 22 1964 2 Sheets-Sheet l INVENTORS WALTER E. ROJECKI 8 BY OTIS R. WITWORTH W 4, e

. ATTORN y 4, 1957 w. E. ROJECKI ETAL 3,329,561

' TENSION APPARATUS IN THE ENDLESS FORMING WIRE OF A FOURDHINIER PAPER MACHINE Filed Sept. 22, 1964 2 Sheets-Sheet FIG-3 83 5 44- Q INVENTORS 80 WALTER snoascm a BY OTIS awnwoam ATTORNEYS United States Patent TENSION APPARATUS IN THE ENDLESS FORM- ING WIRE OF A FOURDRINIER PAPER MA- CHINE Walter E. Rojecki and Otis R. Witworth, Watertown, N.Y., assignors to The Black Clawson Company, Hamilton, Ohio, a corporation of Ohio Filed Sept. 22, 1964, Ser. No. 398,167 6 Claims. (Cl. 162-273) This invention relates to Fourdrinier paper making machines, and more particularly, to a novel apparatus for controlling the tension and taking up the stretch in the forming wire.

It is conventional practice to equip a Fourdrinier paper machine with some means for controlling the tension of the endless forming wire and with some means for taking up permanent stretch which develops in the wire over an extended period of operation and also temporary stretch which can result from variable factors such as temperature rises and acceleration loads. Such equipment is essential to maintain uniform wire speed in view of the fact that the wire is driven by friction through the wire drive roll and/or the couch roll.

Accordingly, it is a primary object of the present invention to provide a novel apparatus which will automatically take up any stretch which develops in the wire during operation and, in addition, will continuously maintain a substantially constant tension in the wire during the operation of the paper machine.

As another object, the present invention provides an apparatus for maintaining constant tension in the wire of a Fourdriner paper machine by use of a tension roll which is adapted to provide a force against the wire at a magnitude which varies as the roll moves through a wide angular range about an eccentric parallel axis without the necessity for making manual adjustments.

A still further object of the invention is to provide a fluid operated apparatus which will automatically maintain a constant tension in the wire over an indefinite operational period, and which apparatus is simple in construction, economical to manufacture and adaptable to paper machines of different sizes.

As another object, the invention provides an apparatus for taking up slack and maintaining a constant tension in the wire of a Fourdrinier paper machine by the use of a fluid operated pressure cylinder means which is adapted to provide a controlled variable torque while moving a tension roll about an eccentric parallel axis such that the-forcebetween the tension roll and the wire will vary according to the angular position of the roll and the extent of wrap of the wire around the roll.

A further object of the invention is to provide a novel apparatus which responds instantaneously to the slightest slack that develops in the return run of the forming wire of a Fourdrinier paper machine as a result of the fluctuations of temperature and the load on the machine.

3,329,561 Patented July 4,1967

Referring to the drawings, which illustrate a preferred I embodiment of the invention, the Fourdrinier paper machine, which is shown somewhat schematically in FIG. 1, includes the basic components of a breast roll 10, a suction couch roll 11, table rolls 12 and suction boxes 13. The endless forming wire W travels continuously from the breast roll 10 to the couch roll 11 and downwardly around a drive roll 15, which is located just beyond and below the level of the couch roll 11 in such a position that the wire wraps around a substantial angular portion thereof. A-series of wire return rolls 16 and 17 are provided to direct the path of the wire along its return run. Commonly, the return rolls 16 and 17 are mounted in the fixed position shown during operation of the machine but are adapted to be moved to an upper position, as shown by the dotted lines, when it is necessary to change the wire W. The present invention is directed primarily to apparatus for taking up any permanent or temporary slack which develops in the wire W and for simultaneously maintaining the tension in the return run of the wire at a predetermined value. This value is selected according to the normal operating load on the wire W, which is determined by operational variables such as the suction box vacuum, speed, and sheet weight. 'In general, the apparatus of the invention employs a pair of wire return rolls 16 which are spaced in parallel relation across the return run of the wire W on the same side of the wire. Preferably, the wire return rolls 16 are arranged at the same elevation, as shown. Spaced substantially midway between the wire return rolls 16 but on the opposite side of the wire W, is a tension roll 20' which is adapted to move vertically along the are 21 about the axis 23.

Referring to the detailed views of the apparatus, as shown in FIGS. 2 and 3, the tension roll 20 is .supported for movement along the are 21 by a pair of arms 25 and l 26, which are rigidly mounted to a torque member 28 Still another object of the invention is to provide a novel fluid operated apparatus for maintaining a constant tension in the wire of a Fourdrinier paper machine during an indefinite period of operation, and which apparatus includes a fluid lock in the fluid supply system in the event the fluid pressure fails.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims;

In the drawings:

FIG. 1 is a somewhat schematic and fragmentary view in side elevation of the wire section of a Fourdrinier paper machine showing the relation of the apparatus of the invention with the major components of the machine;

by a suitable key (not shown). The torque member 28, which is preferably in the form of a round solid shaft, is rotatably mounted in the bearings 30 which are located outwardly of the arms 25 and 26 and mounted to the frame 31. It can be seen from this arrangement that the arms 25 and 26 are adapted to rotate as a unit about the axis 23 as the torque member 28 is rotated. Furthermore, since the torque member 28 is spaced parallel to the wire return rollers 16, the tension roll 20 will be maintained parallel to the rollers 16 at all times during the movement of the tension roller 20 along the are 21.

As shown in FIG. 3, the torque member 28 extends on one end through a bearing 30 and is connected for rotation with a shaft 32 by the coupling 34 which includes a suitable key (not shown). Bearings 37 and 38 are provided for rotatably mounting the shaft 32 about the axis 23 aligned with the torque member 28. A lever 40 is connected to the shaft 32 so that movement of the lever 40 will rotate the torque member 28 and the arms 25 and 26.

tion 46. The cylinder portion 46 is pivotally mounted to the bracket 48 by the pin 49. As shown in FIG. 2, when as the piston rod 44 is extended by pressure within the cylinder portion 46, thelever 40, torque member 28, and the arms and 26 are rotated clockwise about the axis 23. As can be seen from FIG. 1, this motion causes the tension roller 20 to move upwardly between the wire return rolls 16 in order to take up the slack or increase the tension within the forming wire W.

Rigidly mounted to the sides of the lever 40, by the bolts 51, are a pair of brackets 52 which serve to support another fluid operated pressure cylinder, generally identified as 55, which is pivotally mounted in brackets 52 by the connecting pin 57. The piston rod 59, which extends from the cylinder portion 60, is connected pivotally to the bracket 62 by the pin 63. This arrangement of the pressure cylinders 42 and 55, enables them to work together in order to hold the tension roll 20 against the forming wire W. By constructing the shaft 32 separate from the torque member 28, the mechanism which includes the pressure cylinders 42 and 55 and the lever can be mounted along the side of a Fourdrinier paper machine Without regard to the width of the forming wire W. Thus this torque producing mechanism is adaptable for use on paper machines of different widths so that only the length of the tension roll 20 and the torque member 28 has to be modified.

Referring to the schematic diagram of FIG. 4, it can be seen that the forces F and F which are produced by the pressure cylinders 42 and 55, respectively, work together, in a cooperative manner, to urge the lever 40 and the shaft 32 in a clockwise direction. In this manner, the pressure cylinder 55 serves to compensate for the torque produced on the shaft 32 by the weight W of the tension roller 20, and the pressure cylinder 42 produces a torque on the shaft 32 urging the foller 20 against the wire W for producing the tension forces T within the wire W.

As the tension roller 20 moves upwardly along the are 21, it becomes apparent that the counterclockwise torque on the shaft 32 being produced by the weight W of the tension roller 20 becomes progressively less. For this reason, the clockwise torque produced on the shaft 32 by the pressure cylinder 55 must be reduce-d accordingly in order for the roller 20 to remain counter balanced.

Furthermore, as the roller 20 moves upwardly along the are 21, the angle of wrap of the wire increases and it be comes necessary to increase the force with which the roller 20 contacts the wire W in order to maintain a constant tension T in the wire W. For this reason, the clockwise torque produced on the shaft '32 by the cylinder 42 must be progressively increased.

By arranging the pressure cylinders 42 and 55 in the manner as shown in FIG. 4, it can be seen that as the tension roller 20 moves upward along the are 21, the moment arm M increases and the moment arm M decreases. Thus, as the tension roller 20 moves upward in order to take up stretch within the wire W, the pressure cylinder 42 becomes more effective in producing a clockwise torque on the shaft 32 while the pressure cylinder 55 becomes less efiective. By properly arranging the pressure cylinders 42 and 55, the resultant clockwise torque can be made to vary in such a manner that the tension T in the wire W remains constant regardless of the position of the roller 20 along the are 21.

In one satisfactory construction of apparatus according to the invention, the major components are arranged approximately according to the following dimensions:

D=24" Angle Z25 maximum. E=52%" From the above description, it can be seen that the pressure cylinders 42 and 55 cooperate to produce a controlled variable torque on the torque member 28. This torque, in turn, produces a variable upward force by the tension roller 20 against the wire W so as to produce a constant tension T in the wire W independent of the angular position of the tension roll 20 about the axis of rotation 23.

While additional pressure cylinders could be arranged to produce a substantially constant tension, it has been determined that the tension produced by the combination of two pressure cylinders, as described above, provides a desirable, economical and compact arrangement.

A fluid pressure system for operating the pressure cylinders 42 and 55 is shown schematically in FIG. 5. While a pneumatic system is preferred, primarily due to the cushioning effect which accompanies a pneumatic system, it is to be understood that a hydraulic system could be employed to produce satisfactory results. Referring to FIG. 5, a pressure sensing switch is installed in the air supply line 82 which divides into separate lines, one of which leads to each of the pressure cylinders through a pressure regulator valve 83. A solenoid operated air valve 85 is provided in each of the air lines between the regulator valve and the pressure cylinder, and is controlled by electrical leads 88 from the pressure sensing switch 80.

This control system is provided as a safety precaution in the event that the pressure within the supply line 82 should fail. The pressure sensing switch 80 is preset to close the valves 85 if the pressure within the line should drop below a predetermined value, in which event, the closing of the valve 85 locks the pressure with in the pressure cylinders 42 and 55 and thus prevents the tension roller 20 from dropping downwardly which would remove the tension in the wire W. A suitable audible signal (not shown) can be operated also by the pressure sensing switch 80 in order to indicate immediately the failure of the line pressure.

Referring again to FIG. 2, a damping device, generally referred to as 90, is attached to the pressure cylinder 42 and includes a hydraulic cylinder 92 and piston 93 which serves to damp the vibrations produced by the wire on the tension roll 20. As shown, the hydraulic cylinder 92 is carried by the piston rod 44, and the piston rod 93 is connected to the cylinder 42 by a suitable bracket 95.

From the above description, it becomes apparent that the apparatus of the present invention accomplishes two major results. That is, the apparatus provides one movable roll with sufiicient travel for automatically taking up the permanent stretch which develops in the wire W and simultaneously maintains a substantially constant tension within the wire at a predetermined value. Once this value has been determined and the pressure regulating valves 83 have been set, it is no longer necessary to check the apparatus nor to make periodic manual adjustments according to the permanent stretch which develops in the wire. In fact, the entire fluid operated mechanism can be completely covered by a housing in order to seal out paper fibers, dust, and the like which could prevent the pressure cylinders 42 and 55 from operating smoothly.

Of specific importance is the feature that the tension roller 20 will maintain a constant tension in the forming wire throughout the usable angular movement of the tension roll 20 about the axis of rotation 23. As a result, the tension roll 20 will not only maintain constant tension within the wire but serves efiectively as a combined stretch roll to the extent that a separate stretch roll is no longer required.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein with-out departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. Apparatus for maintaining constant tension and taking up permanent and temporary stretch in the endless forming wire of a Fourdrinier paper machine in combination with a pair of parallel spaced wire return rolls mounted on the same side of the wire, said apparatus comprising a tension roll spaced between said wire return rolls on the opposite side of the wire, a support arm connected to each end of said tension roll, a torque member rigidly connecting said arms, means rotatably supporting said torque member to provide for movement of said tension roll through a substantial angular range, a lever, means rigidly connecting said lever to said torque member, at least two pressure cylinder means pivotally connected to said lever, means mounting said cylinder means in relation to said lever to provide a controlled variable torque on said member and said tension roll corresponding to the angular position of said arms to produce a substantially constant wire tension as said roll moves vertically in relation to said wire return rolls, and means for supplying a constant fluid pressure to said pressure cylinder means.

2. Apparatus for maintaining constant tension and taking up permanent and temporary stretch in the endless forming wire of a Fourdrinier paper machine in combination with a pair of parallel spaced wire return rolls mounted on the same side of the wire, comprising a tension rol-l spaced between said wire return rolls on the opposite side of the wire, a support arm connected to each end of said tension roll, a torque member rigidly connecting said arms, means rotatably supporting said member to provide for movement of said tension roll throughout a substantial arc in relation to said wire return rolls to take up stretch in the wire, a plurality of fluid operated pressure cylinders, means connecting said cylinders to said torque member, and means arranging said pressure cylinders in predetermined relationship with said connecting means so that application of a constant fluid pressure to said pressure cylinders produces a variable torque on said torque member for moving said tension roll throughout said arc while maintaining a substantially constant tension within the wire.

3. Apparatus for maintaining constant tension and taking up permanent and temporary stretch in the endless forming wire of a Fourdrinier paper machine in combination with a pair of parallel spaced wire return rolls mounted on the same side of the wire, said apparatus comprising a tension roll spaced between said wire return rolls on the opposite side of the wire, a support arm connected to each end of said tension roll, a torque member rigidly connecting said arms, means rotatably supporting said torque member to provide for movement of said tension roll through a substantial range, a shaft, means removably connecting said shaft to said torque member, a lever rigidly connected to said shaft, pressure cylinder means pivotally connected to said lever, means mounting said cylinder means in relation to said lever to provide a controlled variable torque on said member corresponding to the angular position of said arms to produce a substantially constant tension in the wire as said tension r011 moves vertically in relation to said wire return rolls, and means for supplying a constant fluid pressure to said pressure cylinder means.

4. Apparatus for maintaining constant tension and taking up permanent and temporary stretch in the endless forming wire of a Fourdrinier paper machine in combination wtih a pair of parallel spaced Wire return rolls mounted on the same side of the wire, said apparatus comprising a tension roll spaced substantially midway between said wire retu-rn rolls on the opposite side of the wire, a support arm connected to each end of said tension roll, a torque member rigidly connecting said arms, means rotatably supporting said torque member to provide for movement of said tension roll through a substantial angular range, a shaft connected to said torque member, a lever rigidly connected to said shaft, at least two pressure cylinder means pivotally connected to said lever, means mounting said cylinder means in relation to said lever to provide a controlled variable torque on said member corresponding to the angular position of said arms to produce 'a substantially constant tension in the wire as said tension roll moves vertically in relation to said wire return rolls, and means for supplying a constant fluid pressure to said pressure cylinder means.

5. Apparatus for maintaining constant tension and taking up permanent and temporary stretch in the endless forming wire of a Fourdrinier paper machine in combination with a pair of parallel spaced wire return rolls mounted on the same side of the wire, said apparatus comprising a tension roll spaced between said wire return rolls on the opposite side of the wire, a support arm connected to each end of said tension roll, a torque member rigidly connecting said arms, means rotatably supporting said torque member to provide for movement of said tension roll through a substantial angular range, a shaft removably connected to said torque member, a lever rigidly connected to said shaft, a pair of pressure cylinders pivotally connected to said lever, means for mounting said cylinders in relation to said lever to provide a controlled variable torque on said member corresponding to the angular position of said arms to produce a substantially constant tension in the wire as said tension roll moves vertically in relation to said wire return rolls, and dampening means cooperatively connected to said tension roll for absorbing the vibrations produced by the wire moving over said tension roll.

6. Apparatus for maintaining constant tension and taking up permanent and temporary stretch in the endless forming wire of a Fourdrinier paper machine in combination with a pair of parallel spaced wire return rolls mounted on the same side of the wire, said apparatus comprising a tension roll spaced between said wire return rolls on the opposite side of the wire, a support arm connected to each end of said tension roll, a torque member rigidly connecting said arms, means rotatably supporting said torque member to provide for movement of said tension roll through a substantial angular range, a lever means rigidly connecting said lever to said torque member, a pair of pressure cylinders each having one end pivotally connected to said lever, means for pivotally mounting the opposite ends of said cylinders in spaced relationship to said lever to provide a controlled variable resultant torque on said member corresponding to the angular position of said arms to produce a substantially constant tension in the wire independent of the angular position of said arms, and means for supplying a constant fluid pressure to said pressure cylinders.

References Cited UNITED STATES PATENTS S. LEON BASHORE, Primary Examiner. 

3. APPARATUS FOR MAINTAINING CONSTANT TENSION AND TAKING UP PERMANENT AND TEMPORARY STRETCH IN THE ENDLESS FORMING WIRE OF A FOURDRINIER PAPER MACHINE IN COMBINATION WITH A PAIR OF PARALLEL SPACED WIRE RETURN ROLLS MOUNTED ON THE SAME SIDE OF THE WIRE, SAID APPARATUS COMPRISING A TENSION ROLL SPACED BETWEEN SAID WIRE RETURN ROLLS ON THE OPPOSITE SIDE OF THE WIRE, A SUPPORT ARM CONNECTED TO EACH END OF SAID TENSION ROLL, A TORQUE MEMBER RIGIDLY CONNECTING SAID ARMS, MEANS ROTATABLY SUPPORTING SAID TORQUE MEMBER TO PROVIDE FOR MOVEMENT OF SAID TENSION ROLL THROUGH A SUBSTANTIAL RANGE, A SHAFT, MEANS 